Relay circuit



Patented Dec. 9, 1941 RELAY cmcorr Everett T. Burton, Mlllburn, N. J., assignor to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation 01' New York Application November 2, 1939, Serial No. 302,570

Claims.

This invention relates to a relay circuit and particularly to a vibrating circuit for the production of electrical oscillations.

An object of the invention is the production of electrical oscillations in an economical and efficient manner.

In certain types-of electrical circuit work it may be necessary to continuously operate one or more oscillators for an extended period, possibly several months. While the vacuum tube type of oscillator may of course be used in such work it is relatively expensive to construct and maintain in operation. A relay type of oscillator in accordance with the present invention has been found especially valuable for use in work of this kind as it is relatively low in cost, simple, ,compact and low in maintenance expense.

A feature of the invention is means for periodically changing the direction of current flow through a relay winding whereby the relay armature is caused to vibrate.

A further feature of the invention is starting means for initially setting the relay into operation.

In accordance with a specific embodiment of the invention the relay oscillator includes a twoposition polar relay with two equal windings, a source of power and a series resonant circuit comprising acondenser and an inductance. The condenser of the resonant circuit is charged through one winding of the relay and discharged through the other. Vibration of the relay armature is caused by current reversals in the charge path and the discharge path resulting from the action of the resonant circuit. The period of these vibrations is governed substantially by the values of the condenser and inductance of the resonant circuit.

In accorclancewith a modification of the invention a single winding polar relay is utilized.

A complete understanding of the arrangements contemplated by the invention and an appreciation of the various features thereof may be had from consideration of the subsequent detailed description and the accompanying drawing in which:

Fig. 1 illustrates a vibrating relay circuit which embodies features of the present invention;

Fig. 2 illustrates an alternative form of the output circuit illustrated in Fig. 1 which may be used to advantage when a small amount of output current at a low voltage is desired;

Fig. 3 illustrates a second alternative form of the output circuit which may be used to advantage when desired;

Fig. 4 illustrates a relay circuit of the nature shown in Fig. 1 modified by the addition of a start circuit; and

Fig. 5 illustrates a modification of the vibrating relay circuit which utilizes a single winding relay instead of the two-winding relay illustrated by the circuit of Fig. 1.

Referring now to the drawing, there is shown in Fig. 1 a relay circuit including a two-position polar relay ll provided with two equal windings l2 and i3, an armature l5 and two opposed contacts l6 (mark) and I! (space). Battery 2| is connected in series with winding I3 through key 22. Output circuit 23 is connected across variable condenser 25; condenser 25 together with inductance 26 comprises a tuned series resonant circuit. Condensers 21 and 4| and re-- sistance 42 are provided in order to suppress sparking at the relay contacts.

While the magnitudes of the various elements may, of course, be varied in accordance with varying operating conditions one embodiment of the invention which has operated successfully utilized an inductance (corresponding to inductance 2B) of 20 henries, a capacity (corresponding to condenser 25) of 11 microfarads, two capacities of microfarad each (corresponding to condensers 21 and 4|) and a resistance of ohms (corresponding to resistance 42) The inductance of the relay windings was very small in comparison to that of inductance 26 and need not be taken into account when considering the operation of the circuit. A battery of 48 volts (corresponding to battery 2!) was provided. The circuit operated at a frequency of 5 cycles per second.

In order to describe the operation of the air cult of Fig. 1, let us assume that, with armature [5 in engagement with contact l6 as shown, key 22 be closed. Condenser 25 now takes a charging current from source 21 over a path traced from the plus side of battery 2!, condenser 25, inductance 26, conductor 43, armature l5, contact l6, winding l3 of relay ll, key 22 to the minus side of battery 2i. this direction through winding I 3 tends to hold armature l5 in engagement with contact is.

a large amount of output power is During the initial flow of this charging cur- Current flowing in its direction therefore, and flows through winding l3 in the opposite direction. Flow of current through winding l3 in this new direction causes armature l5 to leave contact l6 and to move into engagement with contact I1. During the short transition period when armature I5 is not in engagement with either contact l6 or H, flow of current through winding I 3 in the lastmentioned direction is maintained, the current path now including condenser 21 and resistance 42 of the spark killer circuit.

After armature l5 engages contact ll, discharge of condenser 25 is continued over a new 'path traced from condenser 25, conductor 45, winding I2, contact 1, armature 5, conductor 43 and inductance 26. Flow of current through winding |2 in this direction tends to hold armature IS in engagement with contact l1.

During the initialflow of the current in the discharge direction, inductance 26 stores up magnetic energy in its field, the inductance tending at first to retard the flow of current in the discharge direction and, later, tending to aid the flow in the manner described above with reference to the flow of charging current. When the condenser voltage reaches zero, 1. e., when the condenser is completely discharged, the energy of the magnetic field of inductance 26 causes the flow of current to continue until the condenser is recharged to the opposite polarity. when the magnetic fleld has died out, condenser 25 again begins to discharge thereby resulting in reversing the direction of current new in the path last traced. Flowof current through winding l2 in this new direction causes armature l5 to leave contact I! and to move into engagement with contact |6 whereupon the entire cycle is repeated. During the short transition period when armature I5 is not in engagement with either contact I! or l6, flow of current through winding 2 in the direction last referred to is maintained, the current flowing to winding l2 through resistance 42 and condenser 4| of the spark killer circuit.

In instances when output voltage of essentially sine wave form is required, output line 23 is connected across condenser 25 as illustrated where the harmonic components of the wave are low; this output line may be associated in suitable manner-with the load circuit. This connection is suitable, however, only if the load circuit impedance be sufliciently high that the effectiveness of the condenser 25 as a tuning element is not seriously impaired.

In certain instances a small amount of output current at a low voltage may be required. In

.such case the circuit of Fig. 1 may be; modified In the instance of Fig. 2, however, the output line 55 is not connected across the condenser of the series resonant circuit as in Fig. 1, but is connected across a supplementary condenser 56 of relatively large capacity, a suitable coupling transformer 51 being included in the connection. The circuit functions in the manner discussed above in connection with Fig. 1 to produce an oscillation across condenser 56 which is transmitted into output line 55 through transformer 51.

In instances when a high current output is required a vacuum tube amplifier may be utilized. A single stage negative grid amplifier of a suitable type for the purpose is illustrated in Fig. 3. Here again as in the case of thecircuit of Fig. 2, the arrangement is the same as that of Fig. 1 except for the output circuit and only the portion of the circuit below the dotted line X-X is shown. Inductance 7| of Fig. 3 corresponds to inductance 26 of Fig. 1,,condenser 12 corresponds to condenser 25 and conductor 13 corresponds to conductor 45.

The. amplifier circuit includes two vacuum tubes 8| and 82, vacuum tube 8| being provided with cathode 83, grid and anode 86 and vacuum tube 82 being provided with cathode 81, rid 9| and anode 92. Anodes 86 and 92 are connected in parallel to primary winding 95 of the output transformer; the secondary winding 96 of the output transformeris connected to the load.

In operation the alternating current wave appearing across condenser 12 is applied to grid 85 through potentiometer 91. This current is amplified by vacuum tube 8| in the usual manner and is supplied to line I through primary winding 95 and secondary winding 86 of the output transformer. A portion of the amplified wave is applied to grid ill of vacuum tube 82 through a comparatively large condenser H2. This portion of the wave is amplified by vacuum tube 82 and is also supplied to line through the output transformer, being superimposed on to vacuum tube 82 and amplified thereby is in reverse phase with respect to the amplified output of vacuum tube 8|. This scheme of amplification has been found to produce an output of reasonably low distortion. The peak-to-peak voltage swing occurring on condenser 12 is higher than the battery voltage and may approach twice the battery voltage. It will be apparent, therefore, that by the use of a suitable single-stage vacuum tube amplifier, as illustrated, considerable output power will be made available.

In the instance of the circuit illustrated in Fig. 1 it is apparent that should the armature be resting on the space contact II, when key 22 is closed the circuit will not of its own accord establish a state of oscillation. While the circuit may of course be set into operation by manually moving the armature to contact l6, a starting arrangement of the nature illustrated in Fig. 4 may be utilized for greater convenience. With the exception of the starting arrangement, the circuit of Fig. 4 is the same as that of circuit l, relay 8 with windings H9 and |2| and contacts I22 (mark) and |-23 (space) corresponding to relay II with windings i2 and I3, and contacts l6 and resistance I25 corresponding to resistance 42.

key I26 corresponding to key 22, inductance I21 corresponding to inductance 26, variable condenser I4I corresponding to variable condenser 25, and so on. The starting arrangement which has been added to the circuit of Fig. 4 comprises resistance I42 and condenser I43 connected in series between mark contact I22 and ground I45. Condenser I43 is shunted by a high resistance I46.

- In one embodiment of the circuit operated successfully by applicant, resistances of 50000) and megohm (corresponding respectively 'to resistances I42 and I46) and a capacity of 2 microfarads (corresponding to condenser, I43) were utilized. The magnitudes of the other elements were as listed above in reference to Fig. 1.

The operation of the circuit of Fig. 4 as a whole is the same as that of the circuit of Fig. 1 and it will be described at this point only sulficiently to illustrate the operation of the starting arrangement. When the operation of the relay is interrupted by opening key I26 and disconnecting battery' I41, condenser I43 discharges through shunt resistance I46 to ground I45. Assuming that armature I5I is in engagement with contact I22 when key I26 is again closed, the relay will be immediately set into operation as described above in connection with Fig. 1. Should armature I5I be in engagement with contact I23, however, when key I26 is closed, condenser I43 will be charged over' a path traced from battery I41, key I26, winding I2I of relay H8, conductor I52. resistance I42, condenser I43 to ground I45. Current flowing through winding I2I over this path operates armature I5I to engage contact I22 whereupon the relay starts to oscillate as described above in connection with the circuit of Fig. 1. During regular operation of the circuit the effect of the start circuit is negligible amounting only to a shunt across winding I2I.

Referring now to Fig. 5 a vibrating relay circuit is disclosed 'which, while operating in a manner generally similar to the circuit of Fig. 1, utilizes a single winding relay instead of a twowinding relay. Polar relay IN is provided with armature I12 and two contacts I13 and I15, mark and space respectively. Battery I16 is connected in series with contact I13 through key I11. Output circuit I8I is connected across variable condenser I82; condenser I82 together with inductance I83 comprises a tuned series resonant circuit.

In order to describe the operation of the circuit of Fig. 5, let us assume that, with armature & in engagement with contact I13 as shown, key

I11 be closed. Condenser I82 now becomes charged over a circuit traced from the plus side of battery I16, condenser I82, inductance I83, conductor I85, winding of relay I1I (the resiste ance of fixed resistor I86 being higher than that of the relay winding), armature I12, contact I13, key I11 to the minus side of battery I16. Current flowing in this direction through the winding of relay I1I tends to hold armature I12 in engagement with contact I13.

During the initial flow of-this charging current, inductance I83 stores up magnetic energy in its field thereby forcing condenser I82 to charge gradually. As the voltage on condenser I82 increases, the current eventually begins to decrease and the magnetic energy stored in inductance I83 begins to return to the circuit and aids the current fiow therein. The voltage on the condenser eventually exceeds the battery voltage after which the current flow is maintained entirely by the magnetic energy supplied by inductance I 83. At such time as the magnetic field of inductance I83 entirely disappears, condenser I82 is charged to a potential considerably in excess of that of battery I16. The current flowing in the path traced above, now reverses its direction therefore, and flows through the winding of relay I1I in the opposite direction. Flow of current through the relay winding in this new direction causes armature I12 to leave contact I13 and to move into engagement with contact I15.

After armature I12 engages contact I15, discharge of condenser I82 is continued over a new path traced from condenser I 82, conductor I81, contact I15, armature I12, winding of relay I1I, conductor I and inductance I83. Passage of current through the winding of relay I1I in this direction tends to hold I12 in engagement with contact I15.

During the initial flow of the current in the discharge direction, inductance I83 stores up magnetic energy in its field, the inductance tending at first to retard the flow of current in-the discharge direction and, later, tending to aid the flow in the manner described previously. When the condenser voltage reaches zero, the energy of the magnetic field of inductance I83 causes the flow of current to continue until condenser I82 is recharged to the opposite polarity. When the magnetic field has died out, condenser I82 again begins to discharge thereby resulting in reversing the direction of current fiow in the path last traced. Flow of current through the winding of relay I1I in this new direction causes armature I12 to leave contact I15 and to move into engagement with contact I13 whereupon the entire cycle is repeated.

While specific embodiments of the invention.

have been selected for detailed description, the invention is not, of course, limited in its application to the embodiments disclosed. The embodiments described should be taken as illustrative of the invention and not as restrictive thereof.

What is claimed is: t

1. A vibrating relay circuit including a polar relay having two operating windings and an armature adapted to engage either of two opposed contacts, a potential source and a resonant circuit, engagement of said armature with one of said contacts being efiective to connect said resonant circuit in series with one of said windings and said potential source and engagement of said armature with the other of said contacts being effective to connect said resonant circuit in series with the other of said windings.

2. A vibrating relay circuit including a polar relay having an operating winding, an armature, and two opposed contacts, a potential source, engagement of said armature and one of said contacts being effective to establish a fiow of current from said potential source through said winding inione direction, and means effective upon establishment of said current fiow to re verse the direction thereof, flow of current through-said winding in the reversed direction being effective to cause said armature to engage the other of said contacts, said means being effective also to again reverse the direction of current flow through said winding after said armature has engaged said other contact.

3. A vibrating relay circuit including a polar relay having an operating winding, an armature,

gagement of said armature and one of said contacts being effective to establish a flow of current from said potential source through said winding in one direction, and means efiective upon establishment of said current flow to reverse the direction thereof, flow of current through said winding in the reversed direction being efiective to cause said armature to engage the other of said contacts, said means being effective also to again reverse the direction of current flow through said winding after said armature has engaged said other contact, said means consisting of a tuned resonant circuit comprising an inductance and a variable condenser connected in series.

4. A vibrating relay circuit including a polar relay having two operating windings and an armature adapted to engage either of two opposed contacts, a source of current, means for causing a flow of current through one of said windings in a direction effective to hold said armature in engagement with one of said contacts, means for causing a flow of current through the other of said windings in a direction effective to hold said armature in engagement with the other of said contacts, and means efiective when current is passed through either of said windings in said respective holding directions to cause a reversal of direction of the current through said respective winding; passage of current through either of said windings in the reversed direction being effective to cause movement of said armature from. the contact with which it is engaged to .the opposed contact. I V 5. In combination a polar relay having two operating windings and an armature adapted to engage either of two opposed contacts, a poten--. .tial source, a condenser, a path for charging said condenser from said potential source, said charging path being efiective to conduct current through through one of said windings in a direction effective to hold said armature in engageand two opposed contacts, a potential source, en-

direction being effective to cause movement of said armature from the contact with which it is in engagement to the opposing contact, said lastmentioned means including an inductance.

7. A vibrating relay circuit including a polar relay having two operating windings, an armature and two opposed contacts, a potential source, a resonant circuit, one of said contacts being connected in series with one of said operating windings, said potential source and said resonant circult, the other of said contacts being connected in series with the other of said operating windings and said resonant circuit, and a network including a capacity shunted by a resistance connected in series with 'saidpotential source, said first winding and ground.

ment with one of said contacts, a path for disof said contacts, and means eifective upon pas- 1 sage of current in either of said paths in said holding direction to cause a reversal of direction of current through the respective winding; passage of current through either winding in the reversed direction being effective to cause movement of said armature from the contact with which it is in engagement to the opposing circuit.

6. In combination a polar relay having two operating windings and an armature adapted to engage either of two opposed contacts, a potential source, a condenser, a path for charging said condenser from said potential source, said charging path being effective to conduct current through one of' said windings in a direction ef fective to hold said armature in engagement with one of said contacts, a path for discharging said condenser, said discharging path being effective to conduct current through the other of said windings in a direction effective to hold said armature in engagement with the other of said contacts, and means efiective upon passage of current in either of said paths in said holding direction to cause a reversal of direction of current through the respective winding; passage of current through either winding in the reversed 8. A vibrating relay circuit including a polar relay having two operating windings, an armature and two opposed contacts, a potential source,

engagement of said armature and one of said contacts being efiective to establish a flow of current from said potential source through one of said windings in one direction, means effective upon establishment of said current flow to reverse the direction thereof, flow of current through said winding in the reversed direction being efiective to cause said armature to engage the other of said contacts, said means consisting of a tuned resonant circuit comprising an inductance and a variable condenser connected in series, and an output circuit connected across said condenser, said output circuit including an am- 9. A vibrating relay circuit including a polar relay having two operating windings, an armature and two opposed contacts, a potential source, a resonant circuit, engagement of said armature with one of said contacts being effective to connect said resonant circuit in series with one of said windings and said potential source and engagement of said armature with the other of said contacts being efiective to connect said resonant circuit in series with the other of said windings, and means efiective when said relay is in non-vibrating condition with said armature in engagement with said other contact for establishing a flow of current from said potential source through the winding in series therewith in a direction effective to cause movement of said armature from the contact with which it is engaged to the opposed contact.

10. A vibrating relay circuit including a polar relay having two operating windings, an armature and two opposed contacts, a potential source, a resonant circuit, engagement of said armature with one of said contacts being effective to connect said resonant circuit in series with one of said windings and said potential source and engagement of said armature with the other of said contacts being effective to connect said resonant circuit in series with the other of said windings, and means effective when said relay is in nonvibrating condition with said armature in engagement with said other contact for establishing a flow of current from said potential source through the winding in series therewith in a direction effective to cause movement of said arma ture from the contact with which it is engaged to the opposed contact, said means including a network comprising a capacity shunted by a resistance connected in series with said potential source, said last-mentioned winding and ground.

EVERETT T. BURTON. 

